There are various kinds of digital signal coding methods in the prior art. One of those digital signal coding methods is to represent different values with a sequence having N numbers. The sequence comprises consecutive N/2 0's and consecutive N/2 1's. A boundary between 0 and 1 can represent different values.
However, due to hardware imperfections or noise interference in transmission, some values of the sequence having N numbers may be changed in transmission, and it is difficult to expect which positions of the sequence are unintentionally changed. That is, although a decoder generates consecutive N/2 0's and consecutive N/2 1's, the sequence inputted in the decoder is not necessarily the original sequence having consecutive N/2 0's and consecutive N/2 1's.
For example, supposing the original transmitting sequence having 20 numbers is [0 0 0 0 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0], i.e., N=20, a transition point of the sequence from 1 transiting to 0 is 14. Nevertheless, due to hardware imperfection or noise interference in transmission, the sequence inputted to the decoder might be [1 1 0 0 1 1 1 1 1 0 0 1 1 0 0 1 1 0 0 0]. If so, since the transition points of the sequence from 1 transiting to 0 are not unique, one needs to determine one transition point within N positions.
The conventional sequence transition point determining method is to use a lookup table. The lookup table method is time costly and wastes hardware resources since the table with 2N kinds of 1's and 0's combination should be stored in advance, and the transition point for each kind of combination needs to be manually determined respectively. Also, when N is changed, the table must likewise be reconstructed, which is costly.
Therefore, there is a desire for a sequence transition point determining method and apparatus thereof.